US20130242278A1 - Projection objective of a microlithographic projection exposure apparatus designed for EUV and a method of optically adjusting a projection objective - Google Patents

Projection objective of a microlithographic projection exposure apparatus designed for EUV and a method of optically adjusting a projection objective Download PDF

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US20130242278A1
US20130242278A1 US13/858,199 US201313858199A US2013242278A1 US 20130242278 A1 US20130242278 A1 US 20130242278A1 US 201313858199 A US201313858199 A US 201313858199A US 2013242278 A1 US2013242278 A1 US 2013242278A1
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Prior art keywords
mirror
projection objective
arrangement
mirror segments
segments
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US13/858,199
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English (en)
Inventor
Hartmut Enkisch
Stephan Muellender
Hans-Juergen Mann
Rolf Freimann
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Carl Zeiss SMT GmbH
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Carl Zeiss SMT GmbH
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Priority to US13/858,199 priority Critical patent/US20130242278A1/en
Assigned to CARL ZEISS SMT GMBH reassignment CARL ZEISS SMT GMBH ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ENKISCH, HARTMUT, MUELLENDER, STEPHAN, FREIMANN, ROLF, MANN, HANS-JUERGEN
Publication of US20130242278A1 publication Critical patent/US20130242278A1/en
Priority to US15/070,757 priority patent/US9720329B2/en
Abandoned legal-status Critical Current

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    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70Microphotolithographic exposure; Apparatus therefor
    • G03F7/70058Mask illumination systems
    • G03F7/702Reflective illumination, i.e. reflective optical elements other than folding mirrors, e.g. extreme ultraviolet [EUV] illumination systems
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/20Exposure; Apparatus therefor
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70Microphotolithographic exposure; Apparatus therefor
    • G03F7/70216Mask projection systems
    • G03F7/70308Optical correction elements, filters or phase plates for manipulating imaging light, e.g. intensity, wavelength, polarisation, phase or image shift
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B17/00Systems with reflecting surfaces, with or without refracting elements
    • G02B17/02Catoptric systems, e.g. image erecting and reversing system
    • G02B17/06Catoptric systems, e.g. image erecting and reversing system using mirrors only, i.e. having only one curved mirror
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B7/00Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/18Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors
    • G02B7/182Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors for mirrors
    • G02B7/198Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors for mirrors with means for adjusting the mirror relative to its support
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70Microphotolithographic exposure; Apparatus therefor
    • G03F7/70216Mask projection systems
    • G03F7/70233Optical aspects of catoptric systems, i.e. comprising only reflective elements, e.g. extreme ultraviolet [EUV] projection systems

Definitions

  • the invention concerns a projection objective of a microlithographic projection exposure apparatus designed for EUV and a method of optically adjusting a projection objective.
  • Microlithography is used for the production of micro structured components such as for example integrated circuits or LCDs.
  • the microlithography process is carried out in a so-called projection exposure apparatus having an illumination system and a projection objective.
  • a mask illumination system
  • Mirrors are used as optical components for the imaging process in projection objectives designed for the EUV range, that is to say at wavelengths of for example about 13 nm or about 7 nm, due to the lack of availability of suitable translucent refractive materials.
  • Typical projection objectives designed for EUV as are known for example from U.S. Pat. No. 7,538,856 B2 can for example have an image-side numerical aperture (NA) in the range from 0.2 to 0.3 and reproduce an object field (for example which is annular) in the image plane or wafer plane.
  • NA image-side numerical aperture
  • NA image-side numerical aperture
  • limits are set in many respects on an increase in the size of the mirror surfaces, that is linked to that increase in the numerical aperture; on the one hand, with increasing dimensions of the mirrors, it becomes increasingly difficult to reduce in particular long-wave surface errors to values below the required limit values, in which respect the larger mirror surfaces require inter alia greater aspheres.
  • increasing dimensions for the mirrors require larger processing machines for manufacture, and stricter requirements are placed on the machining tools used (such as for example grinding, lapping and polishing machines, interferometers and cleaning and coating installations).
  • the manufacture of larger mirrors makes it necessary to use heavier mirror base bodies which, as from a certain limit, can scarcely still be mounted in position or flex beyond an acceptable degree due to the force of gravity.
  • collector mirror of the EUV light source by a plurality of discrete substrate being directed towards a common focal point and then each coated with a multiple layer which is reflective for EUV.
  • collector mirror which for example is in the form of an ellipsoidal mirror one or more actuators are used for orientation of at least one of the substrate relative to a carrier structure, such orientation process being effected in dependence on a measurement of the light which is deflected from a first focal point to a second focal point of the ellipsoidal mirror.
  • An object of the present invention is to provide a projection objective of a microlithographic projection exposure apparatus which permits implementation of higher numerical apertures while at least substantially avoiding the above-described production-engineering problems.
  • a projection objective according to the invention of a microlithographic projection exposure apparatus designed for EUV, for imaging an object plane illuminated in operation of the projection exposure apparatus into an image plane has at least one mirror segment arrangement comprising a plurality of separate mirror segments, wherein associated with the mirror segments of the same mirror segment arrangement are partial beam paths which are different from each other and which respectively provide for imaging of the object plane into the image plane, wherein said partial beam paths are superposed in the image plane and wherein at least two partial beams which are superposed in the same point in the image plane were reflected by different mirror segments of the same mirror segment arrangement.
  • adjacent mirror segments in the mirror segment arrangement according to the invention can be optically seamlessly assembled together or can also be at a finite spacing relative to each other, which can be governed either by the production process or which can also be specifically targetedly provided for the purposes of adjustment of the mirror segment arrangement.
  • partial beam paths which according to the invention are superposed in the image plane and which respectively involve imaging of the object plane (or the mask) into the image plane or wafer plane and the images of which are superposed in the image plane are also referred to here and hereinafter as “simultaneous partial beam paths”.
  • the invention is based in particular on the concept of embodying at least one mirror in the imaging beam path of a projection objective in segment-wise manner, that is to say replacing a monolithic mirror by a mirror segment arrangement comprising a plurality of separate mirror segments.
  • That segment-wise structure of at least one mirror that is to say the replacement thereof by a mirror segment arrangement with separate mirror segments, has substantial advantages in terms of production engineering insofar as on the one hand the maximum diameter to be processed in respect of the mirror segment arrangement according to the invention can be substantially less (only for example of the order of magnitude of 70% or less) than the maximum diameter of a corresponding unsegmented mirror. Under some circumstances consequently manufacture is only now made technologically possible at all, or it is possible to avoid additional capital investment in new and larger production machines.
  • the components to be handled are of a substantially lower (overall) mass, just by way of example of the order of magnitude of 25% or less, in comparison with a corresponding unsegmented mirror. As a consequence of the reduction in the total mass, gravity-induced deformation of the mirror segments or arrangement due to the inherent weight thereof can also be reduced.
  • the disclosure also relates to a projection objective according to the invention of a microlithographic projection exposure apparatus designed for EUV, for imaging an object plane illuminated in operation of the projection exposure apparatus into an image plane has at least one mirror segment arrangement comprising a plurality of separate mirror segments, wherein associated with the mirror segments of the same mirror segment arrangement are partial beam paths which are different from each other and which respectively provide for imaging of the object plane into the image plane, wherein said partial beam paths are superposed in the image plane.
  • the at least one mirror segment arrangement is the reflecting arrangement of the projection objective, which arrangement is last in relation to the beam path at the image plane side.
  • the at least one mirror segment arrangement is the reflecting arrangement of the projection objective having the maximum size of the total optically effective surface (i.e. the total reflecting surface).
  • the at least one mirror segment arrangement has at least three mirror segments, in particular at least four mirror segments.
  • the mirror segments of the same mirror segment arrangement respectively form with each other a continuous reflecting surface interrupted only by transitional regions which are optionally present between adjacent mirror segments.
  • At least two mirror segment arrangements which each have at least two separate mirror segments, wherein associated with the mirror segments of the same mirror segment arrangement are beam paths which are different from each other and which respectively provide for imaging of the object plane into the image plane and which are superposed in the image plane.
  • a respective one of the mirror segments of the one mirror segment arrangement is associated with one of the mirror segments of the other mirror segment arrangement in pair-wise relationship with the same partial beam path.
  • a shutter arrangement so designed that illumination of the at least one mirror segment arrangement can be selectively limited to different mirror segments of said mirror segment arrangement.
  • the invention also relates to a projection objective of a micro lithographic projection exposure apparatus designed for EUV, for imaging an object plane illuminated in operation of the projection exposure apparatus into an image plane, wherein the projection objective comprises a plurality of mirrors, and wherein the mirror of said plurality of mirrors having the maximum size is formed as a mirror segment arrangement comprising a plurality of separate mirror segments.
  • the segmented configuration of the largest mirror (which can be in particular the last mirror at the image plane side) is particularly advantageous since said mirror is particularly relevant for the numerical aperture (NA) at the image side.
  • NA numerical aperture
  • the invention now involves the concept that arranging a suitable obscuration shutter arrangement in the pupil plane of the system makes it possible to provide an obscuration effect which is precisely or at least partially such that the aforementioned mirror segment intermediate spaces lie in the shadow of the obscuration shutter or the shadow of that obscuration out of the pupil plane precisely or at least partially covers the mirror segment intermediate spaces.
  • use is made of the fact that the mirror segment intermediate spaces remain without having a disturbing influence on the imaging properties insofar as just the shadow of the obscuration shutter arrangement is produced on the corresponding region.
  • the shadow projection of the obscuration shutter on the mirror segment arrangement at least partially covers over the mirror segment intermediate spaces. Accordingly, light which—without the obscuration shutter—would be incident on mirror segment intermediate spaces is blinded out/stopped down by the obscuration shutter.
  • an obscuration shutter in a pupil plane of the projection objective wherein the obscuration shutter is so designed that the shadow projection of the obscuration shutter on the mirror segment arrangement covers over the mirror segment intermediate spaces.
  • the at least one mirror segment arrangement is designed in such a way (or with such a “partition” between the individual mirror segments) that mirror segment intermediate spaces between the mirror segments are of a geometry which is at least region-wise of an annular shape or in the shape of a ring segment.
  • Such an annular geometry for the mirror segment intermediate spaces has the additional advantage that no orientation-dependent imaging effects occur, due to obscuration.
  • mirror segment intermediate spaces which are arranged at different azimuth angles and which extend in the radial direction have the effect that certain diffraction orders pass into the region of the mirror segment intermediate spaces and other diffraction orders do not go onto the mirror segment intermediate spaces so that structures involving a mutually different orientation exhibit a different imaging characteristic.
  • the above-described concept however is not limited to mirror segment intermediate spaces which are in ring form or in the shape of a ring segment, so that other geometries are also embraced, in which the mirror segment intermediate spaces lie in the shadow of the obscuration shutter.
  • the obscuration shutter arrangement is to have an influence on the imaging properties, that is as slight as possible or causes little disturbance, it preferably involves a rotational symmetry (without however the invention being restricted thereto).
  • the influence of the obscuration shutter arrangement on the imaging properties is at its slightest when the obscuration shutter arrangement is of an annular geometry as then each structure to be imaged or each diffraction order experiences the same obscuration effect, independently of its orientation.
  • the obscuration shutter arrangement can also be designed with an n-fold symmetry (in particular a four-fold symmetry) with respect to the optical system axis so that the same obscuration is achieved for certain structures or diffraction orders.
  • the invention also concerns a method of producing a projection objective of a microlithographic projection exposure apparatus designed for EUV, for imaging an object plane illuminated in operation of the projection exposure apparatus into an image plane, said projection objective having a plurality of mirrors, wherein at least one of said mirrors is composed of a plurality of separate mirror segments.
  • the composing of said mirror of a plurality of separate mirror segments is made such that at least two partial beams which are superposed in the same point in the image plane were reflected by different mirror segments of said plurality of separate mirror segments.
  • said mirror composed of a plurality of separate mirror segments is the last in relation to the beam path at the image plane side.
  • said mirror composed of a plurality of separate mirror segments is the mirror having the maximum size of the total optically effective surface.
  • At least two of those mirror segments can be optically seamlessly joined together (for example by wringing).
  • at least two of those mirror segments can also be fixed at a finite spacing relative to each other.
  • the invention also concerns a method of optically adjusting a projection objective of a microlithographic projection exposure apparatus, wherein the projection objective has a plurality of mirrors which are oriented during the adjustment operation into their working position for the lithography process, wherein the projection objective has at least one mirror segment arrangement comprising a plurality of separate mirror segments and wherein adjustment is effected in at least two adjustment steps which differ from each other in respect of the mirror segments contributing to imaging of the object plane into the image plane in the respective adjustment step.
  • the invention further concerns an arrangement for optically adjusting a projection objective of a microlithographic projection exposure apparatus, wherein the projection objective has a plurality of mirrors which are oriented during the adjustment operation into their working position for the lithography process, wherein the projection objective has at least one mirror segment arrangement comprising a plurality of separate mirror segments, wherein the arrangement has at least one variable shutter arrangement by means of which illumination of the mirror segment arrangement can be selectively limited to one or more of the mirror segments.
  • FIG. 1 shows a diagrammatic view to illustrate the structure of a projection objective according to an embodiment of the invention
  • FIG. 2 shows a diagrammatic view to illustrate the structure of a projection objective according to a further embodiment of the invention
  • FIG. 3 shows different views to illustrate different possible shutter arrangements in a measuring arrangement according to the invention
  • FIG. 4 shows a diagrammatic view of a possible structure according to the invention to illustrate the structure of a measuring arrangement for simultaneous partial beam paths
  • FIG. 5 shows a diagrammatic view to illustrate a further embodiment of the invention.
  • FIGS. 6-11 show diagrammatic views to illustrate a further aspect of the present invention.
  • FIG. 1 shows a diagrammatic view of the structure of a projection objective 100 in which a mirror is replaced by a mirror segment arrangement comprising separate mirror segments.
  • the basic structure of the projection objective (without the segmentation according to the invention) is known from U.S. Pat. No. 7,538,856 B2 and as such does not belong to the claimed subject-matter of the present application.
  • EUV radiation is incident from an illumination system (not shown) on a mask (reticle) R having structures to be imaged through a slot S which defines the region of the mask R, that is to be illuminated.
  • the projection objective 100 has a plurality of mirrors (in the illustrated embodiment, six mirrors) 110 - 160 , wherein the mirror 160 which is last in relation to the beam path at the image plane side, as is only diagrammatically shown in FIG. 1 , is in the form of mirror segment arrangement comprising separate mirror segments 161 , 162 and 163 .
  • the segmented configuration of the mirror which is last at the image plane side (and at the same time the largest) is particularly advantageous insofar as that mirror is particularly relevant for the numerical aperture (NA) at the image side.
  • the invention however is not limited thereto so that, instead of the mirror which is last at the image plane side, another mirror of the projection objective 100 can also be subdivided into separate segments.
  • a plurality of mirrors that is to say two or more mirrors
  • the number selected in FIG. 1 of three mirror segments is only by way of example and it is also possible to provide segmentation into more or fewer mirror segments (that is to say only two).
  • the projection objective 100 is telecentric at the image plane side but non-telecentric at the object plane side (that is to say on the part of the mask R) in order to avoid interference phenomena with the light incident from the illumination system.
  • a measuring arrangement 170 which is only diagrammatically indicated here serves, as is described in greater detail hereinafter, for measurement of the simultaneous partial beam paths or the superpositioning thereof.
  • FIG. 2 shows a diagrammatic view illustrating the structure of a projection objective 200 according to a further embodiment of the invention, in which there are two mirrors of segmented nature.
  • the basic structure of the projection objective (without the segmentation according to the invention) is known from WO 2009/052932 A1 and as such does not belong to the claimed subject-matter of the present application.
  • the projection objective 200 has six unsegmented mirrors 210 - 250 and 270 and two mirror segment arrangements 260 , 280 of which the mirror segment arrangement 280 which is last in relation to the beam path is subdivided into four mirror segments 281 - 284 while the mirror segment arrangement 260 which is in the third-from-last position in the direction of light propagation is subdivided into six mirror segments 261 - 266 .
  • mirror segment arrangements 260 and 280 and mirrors 270 which are disposed in the last three positions in relation to the beam path on the image plane side are respectively obscured and have a through opening for light incident on the position of the optical axis OA.
  • the mirror 250 which is disposed in the fourth-from-last position in relation to the beam path is not obscured and produces a shadowing defined by its outer peripheral edge in a pupil plane PP of the projection objective.
  • a respective one of the mirror segments 261 - 266 of the mirror segment arrangement 260 with one of the mirror segments 281 - 284 of the other mirror segment arrangement 280 , is associated in pair-wise relationship with the same partial beam path.
  • Both such a pair of mirror segments (namely that comprising the mirror segments 261 and 284 ) and also the corresponding portion a partial beam path are emphasized by arrows in FIG. 2 .
  • the totality of all of those pairs of segments defines a set of simultaneous partial beam paths.
  • a measuring arrangement which is diagrammatically indicated in FIG. 2 and denoted by reference 290 and described hereinafter serves to ensure that on the one hand each partial beam path is stigmatic in itself and on the other hand the images respectively produced by the partial beam paths overlap in the wafer plane in accordance with the respective image structure width.
  • the mirror segments of the mirror segment arrangement are oriented both relative to each other and also (as a whole) relative to the system by way of actuators. Accordingly the invention also concerns a combination with a measuring arrangement and an actuator system which permits adjustment of the mirror segments.
  • the measuring arrangement according to the invention can be both already used during assembly or initial adjustment of the system and also during ongoing operation or in the scanner of the projection exposure apparatus.
  • WO 2007/062808 A1 discloses a “grazing incidence interferometer” for measurement of an active mirror. That interferometer can be used in a similar fashion for measurement of the mirror segment arrangement according to the invention. Furthermore, a system wave front interferometer as is disclosed in US 2008/0144043 A1 can also be used to check the orientation of the overall mirror. When using that interferometer, use is made of the fact that the aberrations of the projection objective are influenced by a variation in mirror position or orientation, wherein those changes in aberration in turn can be detected by means of the system wave front interferometer.
  • FIGS. 3 a - c and FIG. 4 A basic possible embodiment of a measuring arrangement for the simultaneous partial beam paths and their superpositioning is described hereinafter with reference to FIGS. 3 a - c and FIG. 4 .
  • An optical projection system 300 and 400 respectively which is only indicated in FIGS. 3 a - c and FIG. 4 , similarly to the above-described embodiments, includes at least one mirror segment arrangement 310 and 410 respectively, wherein for the sake of simplicity only one further (unsegmented) mirror 320 and 420 respectively is shown.
  • the measuring arrangement of FIG. 4 has at least one detector 455 arranged downstream of the projection objective 400 (only diagrammatically indicated), in the light propagation direction.
  • the measuring arrangement has a measuring light source 401 upstream of the projection objective 400 in the light propagation direction, the measuring light source 401 producing radiation with defined properties in the object plane.
  • the measuring arrangement for the simultaneous partial beam paths and the superpositioning thereof is to perform in particular the following tasks:
  • the measuring arrangement has a selectively acting shutter arrangement 415 for selecting given solid angle regions of the light, which makes it possible to limit the illumination of at least one mirror segment arrangement selectively to different ones of the mirror segments.
  • such a shutter arrangement can be arranged either directly downstream of the mask R (see reference 315 in FIG. 3 a ) disposed in the object plane OP, between two mirrors or mirror segment arrangements 310 and 320 (see reference 316 in FIG. 3 b ) or in the light propagation direction directly upstream of the detector arrangement (see reference 317 in FIG. 3 c ).
  • the shutter arrangement for selection of the partial beam paths by means of the shutter arrangement, it is advantageous to dispose all individual openings in a common shutter plane and to select a respective one thereof by a displaceable shutter.
  • the openings in the shutter arrangement are determined in terms of position and size by the partial beam path produced by the measuring light source 301 and 401 respectively, along the respective pairs of mirrors.
  • an associated shutter opening for each partial beam path there exists an associated shutter opening of respective position, shape and size.
  • the measurement arrangement according to the invention makes it possible in particular to be able to check the respective contribution of the individual partial beam paths to the (overall) image produced in the image plane, separately or in targetedly selectable combinations.
  • Performance of the task in accordance with c), that is to say for measuring the superpositioning of the images produced by at least two partial beam paths in the wafer plane, involves the selectively acting shutter arrangement according to the invention being combined with further measuring arrangements for superpositioning of the images.
  • the measuring arrangement for superpositioning of the images produced by the partial beam paths must evaluate at least one surface element in positionally resolved fashion in the image plane in order to be able to provide information about the superpositioning.
  • the apparatus based on the moiré principle for distortion measurement in accordance with above-mentioned U.S. Pat. No. 7,019,824 B2 can be suitably enlarged, as diagrammatically shown in FIG. 4 :
  • a first pattern 402 arranged in the object plane OP is imaged onto a second pattern 435 arranged in the image plane IP and by superpositioning forms a moiré pattern which in turn can be imaged by a subsequent optical imaging system 445 and recorded by a positional resolving camera 455 .
  • the optical projection system 400 only indicated in FIG. 4 includes at least one mirror segment arrangement 410 , only one further (unsegmented) mirror 420 being shown for the sake of simplicity.
  • the first pattern 402 and the second pattern 435 can be embodied in particular in “parquet-like” fashion in order to obtain information in different spatial directions, with the minimum possible number of measurement steps.
  • a possible method of orienting and adjusting the partial beam paths with respect to each other using that measuring arrangement can take place as follows:
  • a first partial beam path is selected by means of the shutter arrangement 415 and the superpositioning of the image of the first mask 402 arranged in the object plane OP with the second mask 403 arranged in the image plane is observed for that first partial beam path, with the masks 402 , 403 being oriented relative to each other.
  • the distortion in the first partial beam path can be inferred from the first moirépattern which is produced in that case.
  • a second partial beam path is selected by means of the shutter arrangement 415 and produces a second moiré pattern, wherein deviations in that second partial beam path from the first partial beam path lead to differences between the second moiré pattern and the first moiré pattern.
  • Deviations in the optical properties of the second partial beam path from the first partial beam path can be inferred from the deviations between the two moirépatterns.
  • the second partial beam path can be optimized in relation to the first partial beam path in respect of image position and distortion by way of a suitable manipulator system. That step is repeated for all partial beam paths so that as a result all partial beam paths are oriented relative to each other.
  • the position of the shutter arrangement 415 can also be altered in such a way that more than one partial beam path simultaneously contributes to imaging.
  • the individual partial images are superposed incoherently in the image plane to form a multiple partial image which can also be evaluated as described. That combination can be implemented at the same time until opening of all partial beam paths occurs so that as a result the overall projection objective is adjusted with all mirror segment arrangements.
  • FIG. 5 shows a diagrammatic view to illustrate a further embodiment of the invention.
  • FIG. 5 shows a segmentation by way of example of a (comparatively large) rotationally symmetrical mirror which is near the pupil and which has a mirror opening or mirror bore for a beam to pass therethrough.
  • the exit pupil is centrally obscured.
  • a mirror segment arrangement 500 is afforded by the segmentation of that mirror in an initially similar fashion to the above-described embodiments.
  • segmentation in the mirror segment arrangement 500 is effected in dependence on the respectively set illumination setting.
  • the illumination setting used is firstly established.
  • the transitional regions or “cuts” between the individual mirror segments are so selected in that case that no diffraction order is incident on those transitional regions.
  • the illumination setting has four illumination poles 501 - 504 which are respectively turned through 45° relative to the y-axis, the respective diffraction orders being illustrated for horizontally and vertically oriented dense lines respectively.
  • segmentation or division of the mirror segment arrangement 500 into four mirror segments 510 - 540 is adopted, which are respectively arranged in the corresponding four segments turned through 45° with respect to the y-axis in the illustrated coordinate system.
  • the arrangement in FIG. 5 makes it possible on the one hand to compensate for field-constant low-order pupil errors, for example astigmatism and coma.
  • a further advantage with this arrangement that it is only ever necessary to adjust relative to each other those ones of the mirror segments 510 - 540 , which contribute to the diffraction image of the same structure.
  • only two respective pairs of mirror segments are to be adjusted relative to each other, more specifically on the one hand the mirror segments 520 and 540 relative to each other and on the other hand the mirror segments 510 and 530 relative to each other.
  • the relative arrangement for example of the mirror segment 520 relative to the mirror segment 530 or the mirror segment 510 is immaterial. That considerably reduces the demands on adjustment as, in comparison with an adaptive mirror which is used over the full surface area, only half the number of parameters have to be jointly controlled.
  • FIG. 6 shows an embodiment of a mirror segment arrangement 600 which is designed in such a way (or with such a “partition” between the individual mirror segments) that mirror segment intermediate spaces between the mirror segments are of a geometry which is at least region-wise in a ring shape or in the shape of a ring segment.
  • the mirror segment arrangement 600 diagrammatically illustrated in FIG. 6 includes a central mirror segment 610 as the “main mirror”, the size of which can be suitably selected in terms of aspects relating to production engineering, and the main mirror 610 can therefore also be produced with comparatively no problems.
  • the mirror segment arrangement 600 in the illustrated embodiment includes four mirror segments 620 , 630 , 640 and 650 as “secondary mirrors” which are in the form of circular ring segments with substantially radially extending segment intermediate spaces so that they are arranged around the central mirror segment 610 forming the main mirror, at a certain radial spacing relative to the central mirror segment 610 . That radial spacing can be used for example for holder elements, sensor means and/or actuator means.
  • mirror segments 620 , 630 , 640 and 650 are at the minimum possible spacing relative to each other (that is to say in the azimuthal direction with respect to the optical system axis extending in the z-direction in the illustrated coordinate system) so that no structural space worth mentioning is required in the azimuthal direction.
  • FIGS. 7 a and b show diagrammatic views illustrating examples of a respective obscuration shutter arrangement 710 and 720 , as is arranged according to the invention preferably in a pupil plane or in the proximity thereof (as defined hereinafter with reference to FIG. 9 ).
  • the obscuration shutter arrangement 710 of FIG. 7 a is defined for an optical system without central pupil obscuration and the obscuration shutter arrangement 720 of FIG. 7 b is designed for an optical system with central pupil obscuration.
  • the regions which are respectively shadowed by the obscuration shutter arrangement 710 and 720 are respectively identified by 710 a , 720 a and 720 b .
  • the obscuration shutter arrangement 710 and 720 as described hereinafter, is so designed in each case that the shadow it casts on the mirror segment arrangement 600 covers over the radially extending mirror segment intermediate spaces.
  • the aim and purpose of the respective obscuration shutter arrangement 710 and 720 is thus to previously cut out light which, without the obscuration shutter arrangement 710 and 720 , would be incident in the annular gap A between the main mirror 610 and the secondary mirrors 620 - 650 , so that field-dependent effects or field-dependent changes in the imaging characteristics are avoided.
  • the second mirror 820 in the beam path forms a mirror near the pupil.
  • FIG. 9 for the definition of the criterion of “pupil nearness” and also field nearness.
  • the pupil or field nearness respectively can be quantitatively described by way of a parameter P(M) (as described for example in US 2008/0165415 A1), wherein the parameter P(M) is defined as:
  • D(SA) denotes the subaperture diameter
  • D(CR) denotes the maximum principal ray spacing (from all field points or defined over all field points of the optically used field) on the optical surface M in the plane in question.
  • the above-mentioned mirror 820 is preferably disposed in a plane of the projection objective, in which the parameter P(M) is at least 0.8, in particular at least 0.9.
  • An obscuration shutter arrangement 890 (not shown in FIG. 8 ) is also disposed in the pupil nearness in accordance with the foregoing definition.
  • the obscuration shutter arrangement 890 as shown in FIG. 10 a has a ring-shaped obscuration shutter 891 and a central obscuration shutter 892 .
  • FIG. 10 b shows the respective shadowed regions which result out of the action of the obscuration shutter arrangement 890 at the location of the last mirror 880 at the image plane side, wherein reference 891 a denotes the shadow of the ring-shaped obscuration shutter 891 and reference 892 a denotes the shadow of the central obscuration shutter 892 .
  • FIG. 11 diagrammatically shows further possible embodiments of obscuration shutter arrangements 910 , 920 , 930 and 940 . What is common to those obscuration shutter arrangements 910 - 940 is that they each involve a four-fold symmetry.
  • obscuration shutters 911 - 914 and 921 - 924 respectively which are suitable for forming the obscuration shutter arrangements 910 and 920 are arranged in the peripheral direction or azimuthally (with respect to the optical system axis extending in the z-direction in the illustrated coordinate system), and more specifically (with respect to the respective central axis or axis of symmetry), at an angle of 45°, 135°, 225° and 315° respectively with respect to the y-axis.
  • the geometry of the obscuration shutters 911 - 914 is so selected that this affords a cross-shape geometry of the non-shadowed region whereas the geometry of the obscuration shutters 921 - 924 is so selected that this affords a star-shaped geometry of the non-shadowed region.
  • obscuration shutters 931 - 934 and 941 - 944 respectively which are suitable for giving the obscuration shutter arrangements 930 and 940 are arranged in the peripheral direction or azimuthally (with respect to the optical axis extending in the z-direction in the illustrated coordinate system), and more specifically (with respect to the respective central axis or axis of symmetry), at an angle of 0°, 90°, 180° and 270° respectively with respect to the y-axis.
  • the geometry of the obscuration shutters 931 - 934 in FIG. 11 c is so selected, similarly to FIG.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
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  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
US13/858,199 2010-11-05 2013-04-08 Projection objective of a microlithographic projection exposure apparatus designed for EUV and a method of optically adjusting a projection objective Abandoned US20130242278A1 (en)

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US13/858,199 US20130242278A1 (en) 2010-11-05 2013-04-08 Projection objective of a microlithographic projection exposure apparatus designed for EUV and a method of optically adjusting a projection objective
US15/070,757 US9720329B2 (en) 2010-11-05 2016-03-15 Projection objective of a microlithographic projection exposure apparatus

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US41052110P 2010-11-05 2010-11-05
DE201010043498 DE102010043498A1 (de) 2010-11-05 2010-11-05 Projektionsobjektiv einer für EUV ausgelegten mikrolithographischen Projektionsbelichtungsanlage, sowie Verfahren zum optischen Justieren eines Projektionsobjektives
DE102010043498.1 2010-11-05
PCT/EP2011/069308 WO2012059537A1 (fr) 2010-11-05 2011-11-03 Objectif de projection d'un appareil d'exposition microlithographique
US13/858,199 US20130242278A1 (en) 2010-11-05 2013-04-08 Projection objective of a microlithographic projection exposure apparatus designed for EUV and a method of optically adjusting a projection objective

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JP2013543274A (ja) 2013-11-28
CN103189800A (zh) 2013-07-03
US20160195817A1 (en) 2016-07-07
DE102010043498A1 (de) 2012-05-10
TWI579648B (zh) 2017-04-21
JP5950129B2 (ja) 2016-07-13
TW201239542A (en) 2012-10-01
WO2012059537A1 (fr) 2012-05-10
EP2635937B1 (fr) 2015-08-19
KR101909301B1 (ko) 2018-12-10
US9720329B2 (en) 2017-08-01
KR20130102093A (ko) 2013-09-16
EP2635937A1 (fr) 2013-09-11
CN103189800B (zh) 2016-08-10

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